You get a lot of work done at Sigma right? Have a word with Neil Spalding about the top end of a 748RS.
I'm sure I read on the Sigma site that the 748RS race cam snaps the valves open and slams them shut really violently and, even though the valves are extra trick, they're usually breaking apart by 750Km. I seem to remember talk about top end rebuilds every 200 miles
If you can afford that and go DD racing, go for it!
In fact, if you can afford that and go DD racing...got any jobs going at your place?